Method for viewing objects in a lightscattering atmosphere



Jan. 4, 1966 N. D. SMITH, JR

METHOD FOR VIEWING OBJECTS IN A LIGHT-SCATTERING ATMOSPHERE Filed March15, 1963 INVENTOR:

NOYES D. SMITH, JR. BY: WW 2%? HIS ATTORNEY United States Patent3,227,874 METHOD FOR VIEWING OBJECTS IN A LIGHT- SCATTERING ATM'QSPHERENoyes D. Smith, In, Bellaire, Tex., assignor to Shell Oil C0mpany, NewYork, N.Y., a corporation of Delaware Filed Mar. 13, 1963, Ser. No.264,963 4 Claims. (Cl. 25071) This invention relates to a method ofimproving the clarity with which objects can be viewed by a camerasurrounded by an atmosphere that tends to scatter light. Morespecifically this invention deals with a method of observing objectssubmerged in water by means of a television or photographic camera.

One of the most important uses of this invention is in the observationof equipment of underwater wells which are drilled, for example, in theocean floor for the production of oil and gas.

At the present time, wells are being drilled in the ocean floor atdepths of 400 feet and wells at depths of 1000 feet or more arecontemplated in the near future. When Working at these depths it becomesnecessary to maintain a great deal of equipment beneath the surface ofthe water. Many times during the drilling or working on underwater Well,the drilling or other equipment must be temporarily withdrawn from thewell, e.g., to replace a drilling bit, etc., and subsequently laterreplaced. Due to the great depth, the problem of alignment of thedrilling platform above the water with the Well is increased. In theevent that there should be a malfunction of the well equipment or aserious misalignment problem, some means must be provided for observingthe submerged equipment to determine the cause of the trouble or elsethe equipment must be raised to the surface, resulting in a great lossof time and money. Furthermore, with the advent of underwater completiontechniques, many operations, such as bolting various componentstogether, must be manually performed on equipment which is at all timesunderwater. In the past these functions have been performed by a diver.As the depth of the water in which the wells are drilled becomes deeper,the proportion of the time that the diver can devote to useful workdecreases, resulting in further loss of time and money. Although systemshave been devised for performing these manual operations automaticallyfrom the surface, some means must still be provided to observe theunderwater equipment.

It has therefore become common practice when working on underwater wellsto use a television or photographic camera for observation purposeswherever possible. The television or photographic camera is lowered intothe water along with suitable lamps capable of emitting a visiblespectrum for illuminating the area of interest, so that the operators atthe surface may observe the equipment beneath the surface of the water.The use of light in the visible spectrum for underwater television orphotography, however, has the disadvantage that the resulting icture hasvery poor contrast. This is caused by the scattering of the visiblelight rays both by the water and by material, such as dirt particles,which is suspended in the water.

To reduce the scattering of the illuminating light and thereby improvethe clarity of the picture, it appears that light of a longer wavelength than the visible light spectrum, i.e., infrared light, should beused as the illuminating source. Although it is true that using anilluminating source of infrared light will reduce the scattering of thelight due to the water, the material suspended in the water will stillreflect a great deal of the illuminating light back to the camera. Thisreflected light will cause the resulting picture to still have poorcontrast.

It is therefore an object of this invention to provide an improvedmethod of observing underwater equipment.

It is a further object of this invention to provide a method ofimproving the contrast of the images presented to a camera surrounded bya medium which scatters visible light.

Briefly, the above objects are achieved by coating the submerged objectto be viewed with a material that fluoresces and may also phosphorescein the red and/or infrared region of the spectrum (Wave length greaterthan 6100 A.) in response to light of a predetermined frequency;illuminating the object to be viewed with light free from red andinfrared frequencies and which causes said fluorescence; and thenfiltering the light transmitted to the camera with a filter passing onlyred and/ or infrared light. The fluorescent materials are sometimescalled phosphors or prosphorescent substances.

These and other objects of the present invention will be understood fromthe following description taken with reference to the attached drawingswherein:

FIGURE 1 is an isometric view of one form of the underwater apparatuswhich can be used to carry out applicants invention; and

FIGURE 2 is a cross-sectional on a reduced scale showing the surfaceapparatus used with the underwater apparatus of FIGURE 1; and

FIGURE 3 is a cross-sectional elevation view of the apparatus necessaryto practice applicants invention.

Referring to FIGURES 1 and 2 of the drawings, a drilling barge 11 of anysuitable fixed or floatable type is illustrated as floating on thesurface of a body of water 12 and substantially fixedly positioned overa preselected location of the ocean floor 13 by anchor lines 14 and 15running to anchors (not shown) sunk in or on the ocean floor. Equipmentof this type may be used when carrying out well drilling, wellcompletion, or well maintenance operations in water varying from aboutto 1500 feet or more in depth. The drilling barge is equipped with asuitable derrick 16 containing fall lines 17 and a hoist (not shown), aswell as other auxiliary equipment needed during the drilling orservicing of a well. Thus, in this instance the drilling rig is shown asbeing provided with a traveling block 21 to which is secured a pair ofelevators or other suitable means for connecting to the top of a stringof pipe 23, commonly known as a running pipe string or running string,by which equipment may be lowered down to or into a well.

The derrick 16 is positioned over a drilling slot or well 26 whichextends vertically through the barge 11 in a conventional manner. Whenusing the equipment of the present invention, the slot 26 and the barge11 may be either centrally located or extend in from one edge. However,operations with the apparatus of the present invention may be carriedout over the side of the barge without the use of the slot.

An underwater wellhead support base, which is represented by ahorizontally-extending support base or other frame '27, which may have acasinghead 28 secured thereto and centrally positioned thereon, ispreferably anchored to the ocean floor by means of a conductor pipe orsurface casing (not shown) which is attached to the support base 27 andinstalled and preferably cemented in the ocean floor. Secured to thewellhead support base 27 are two or more guide columns 32 and 33 havingguide cables 34 and 35 extending vertically therefrom to the drillingbarge 11 where they are preferably secured to the barge by means ofconstant-tension winches 36 and 37. The guide cables 34 and 35 areprovided for the purpose of guiding pieces of equipment into alignmenton or in the casinghead 28 positioned at the ocean floor.

In FIGURES 1 and 2, a well connector 40 is shown 3 connected to thecasinghead 28 and to the surface by means of a running pipe string 23which extends to the barge 11 and is suspended from the derrick 16.Extending outwardly from the connector device 40 are pairs of guide arms43 and 44 having the outer ends thereof slidably mounted on the guidelines 34 and 35, respectively. The guide system just briefly describedis shown in greater detail in the copending application of Lloyd G.Otteman and John A. Haeber, Ser. No. 102,222, filed Apr. 11, 1961, nowPatent No. 3,143,171, issued Aug. 4, 1964.

In order to observe the well connector 40 once it is below the surfaceof the water, a television camera 50 and suitable illuminating means 51,which according to the invention emit light in the ultraviolet spectrum,are lowered from the barge 11. The camera 50 and illuminating means 51are mounted on a carriage 52 which is suspended from the barge 11 bymeans of a multi-conductor cable 53 which is also used to supply powerto the camera 50 and illuminating means 51 and to transmit thetelevision signals to the surface. A second set of guide cables 54, 55anchored in guide columns 56, 57 and secured to the barge by means ofconstant-tension winches 58, 59 are provided to guide the carriage as itis lowered. Such a carriage and guide system are de scribed in thecopending application of K. W. Foster and R. L. Geer, Ser. No. 250,604,filed Jan. 10, 1963, now Patent No. 3,184,541, issued May 18, 1965.

Referring now to FIGURE 3, there is shown a portion of the object to beviewed, i.e., the well connector 40, which according to the inventionhas on its surface a coating 61 which will fluoresce or phosphoresce inthe infrared and/or red region of the light spectrum when irradiatedwith light of a predetermined frequency, which is preferably in theultraviolet region of light spectrum. Such a coating may consist, forexample, of a paint or lacquer which is transparent to ultraviolet lightand contains a substance which phosphoresces in the red or infraredregion of the light spectrum when irradiated with ultraviolet light.Examples of such a substance would be rhombohedral Al O :Cr andhexagonal ZnS.CdS:Cu- (0.005). The crystals of the former mentionedsubstance, in response to ultraviolet light excitation, emit a spectrumhaving its two most intense lines at 6927 and 6947 angstroms which areat the limit of the red region of the light spectrum, while those of thelatter emit a spectrum which has its maximum intensity a. little above7100 A. which is within the infrared region of the light spectrum. Otherexamples of materials that possess this phenomenon can be found in thebook Luminescene of Solids, by H. W. Leverenz, Wiley and Sons, 1950.

The illuminating means 51, which in the given example may be anysuitable source of ultraviolet light, preferably consists of a quartzmercury arc lamp 62 mounted in a water tight casing 63. A filter 64which passes only the ultraviolet spectrum is placed in the path oflight from the lamp 62. The ultraviolet light, after passing through thefilter 64 and if necessary a lens 65, is focused on the portion of theunderwater equipment to be viewed which causes the aforementionedcoating to give ofl light in the red and/or infrared region of the lightspectrum.

The radiations produced by the coating 61 are transmitted to thetelevision camera 50 through a lens 66 and a filter 67 mounted acrossthe face of the camera 50. The filter 67 is selected to pass only redand infrared light. The red and infrared light, because it has a longerwave length than visible light, will tend to be less scattered by thesurrounding water than the visible light and will thus result in aclearer picture of the viewed object.

While the invention has been described for an underwater televisionsystem, it is understood that a photographic camera may equally well beused in place of the television camera. It is also to be understood thatthe invention is not limited to underwater use but may be used in anylight scattering medium.

I claim as my invention:

1. For use in underwater operations wherein an underwater installationis positioned at or near the ocean floor in a body of water havingsuspended therein light-scattering and reflecting particles in an amountsufficient to substantially reduce observations made on saidinstallation, the method of improving the clarity with which theinstallation may be observed by means of an underwater cameracomprising:

(a) providing a coating on a portion of the installation to be observed,said coating including a substance which fluoresces at a wave lengthgreater than 6100 A. in response to light excitation; V

(b) transmitting light having a wave length shorter than 6100 A. throughsaid body of water to illuminate the portion of the installation to beobserved and cause said fluorescence;

(c) observing the coated portion of said installation by means of saidunderwater camera; and

(d) filtering the light admitted to said camera to pass only light of awave length greater than 6100 A., whereby the illuminating light whichis scattered and/ or reflected back to the camera by the particles inthe water is prevented from entering the camera.

2. A method for use in underwater operations wherein an underwaterinstallation is positioned at or near the ocean floor in a body of waterhaving suspended therein light-scattering and reflecting particles in anamount sufficient to substantially reduce observations made on saidinstallation, said method comprising:

(a) providing a coating on portions of the installation to be observed,said coating including a material which fluoresces at a wave lengthgreater than 6100 A. when excited by ultraviolet light;

(b) transmitting ultraviolet light through said body of water toilluminate said coated portions of said installation and excite saidmaterial;

(c) observing said coated portions of said installation with anunderwater camera; and

(d) filtering the light admitted to said camera to pass only light of awave length greater than 6100 A., whereby the illuminating light whichis scattered and/ or reflected back to said camera by said particles isprevented from entering the camera, and thereby causing the clarity ofthe resulting picture to be improved.

3. A method for use in underwater operations wherein an underwaterinstallation is positioned at or near the ocean floor in a body of waterhaving light-scattering and reflecting particles suspended therein in anamount sufficient to substantially reduce observations made on saidinstallation, said method comprising:

(a) providing at least a portion of said installation with a coatingincluding a lacquer which is transparent to ultraviolet light andcontains minerals which fluoresce at a wave length greater than 6100 A.when excited by ultraviolet light;

(b) transmitting ultraviolet light through said body of water toilluminate a coated portion of said installation and thereby cause saidminerals to fluoresce;

(c) observing the illuminated portion of the installation by means of anunderwater camera; and

(d) filtering the light admitted to said camera to remove the light ofhigher frequency than that of red light, whereby the illuminating light,which is scattered and/or reflected back to the camera by saidparticles, is prevented from entering the camera.

4. A method for use in underwater operations wherein an underwaterinstallation is positioned at or near the ocean floor in a body of waterhaving suspended therein light-scattering and reflecting particles in anamount sufficient to substantially reduce observations made on saidinstallation, said method comprising:

(a) coating the portions of said installation to be observed with alacquer which is transparent to ultraviolet light and contains mineralswhich fluoresce in the infrared region of the spectrum when excited byultraviolet light;

(b) submerging and positioning said installation at a desired locationin said body of water;

(c) transmitting ultraviolet light through said body of water toilluminate a coated portion of said installation, thereby causing saidminerals to fluoresce;

(d) observing the illuminated portion of said installation by means ofan underwater camera; and

(e) filtering the light admitted to said camera to remove the light ofhigher frequency than that of infrared light, whereby the illuminatinglight, which 15 has been scattered and/ or reflected back to the cameraby the particles suspended in said body of water, is prevented fromentering the camera.

References Cited by the Examiner UNITED STATES PATENTS Claudet 250-71Garrison 25071 Urbach 25071 Urbach 25071 Reistle 175-7 Hayes 1757Johnson 16666.5

Burkhardt 250 83.3

RALPH G. NILSON, Primary Examiner.

J. W. LAWRENCE, Examiner.

1. FOR USE IN UNDERWATER OPERATIONS WHEREIN AN UNDERWATER INSTALLATIONIS POSITIONED AT OR NEAR THE OCEAN FLOOR IN A BODY OF WATER HAVINGSUSPENDED THEREIN LIGHT-SCATTER ING AND REFLECTING PARTICLES IN ANAMOUNT SUFFICIENT TO SUBSTANTIALLY REDUCE OBSERVATIONS MADE ON SAIDINSTALLATION, THE METHOD OF IMPROVING THE CLARITY WITH WHICH THEINSTALLATION MAY BE OBSERVED BY MEANS OF AN UNDERWATER CAMERACOMPRISING: (A) PROVIDING A COATING ON A PORTION OF THE INSTALLATION TOBE OBSERVED, SAID COATING INCLUDING A SUBSTANCE WHICH FLUORESCES AT AWAVE LENGTH GREATER THAN 6100 A. IN RESPONSE TO LIGHT EXCITATION; (B)TRANSMITTING LIGHT HAVING A WAVE LENGTH SHORTER THAN 6100 A. THROUGHSAID BODY OF WATER TO ILLUMINATE THE PORTION OF THE INSTALLATION TO BEOBSERVED AND CAUSE SAID FLUORESCENCE; (C) OBSERVING THE COATED PORTIONOF SAID INSTALLATION BY MEANS OF SAID UNDERWATER CAMERA; AND (D)FILTERING THE LIGHT ADMITTED TO SAID CAMERA TO PASS ONLY LIGHT OF A WAVELENGTH GREATER THAN 6100 A., WHEREBY THE ILLUMINATING LIGHT WHICH ISSCATTERED AND/OR REFLECTED BACK TO THE CAMERA BY THE PARTICLES IN THEWATER IS PREVENTED FROM ENTERING THE CAMERA.